In the Mix Cold Weather Masonry8.20.12

Cold Weather Masonry Construction
With winter right around the corner, it is critical to consider several factors that will
dictate the success of masonry construction during the cold weather season. When
ambient temperatures fall below 40o F, deploying a cold weather program will require
some changes in procedures, equipment and supplies to avoid issues caused when mortar
falls below normal temperatures:
Water requirement to reach a given consistency is reduced
A given amount of air-entraining agent yields more entrained air
Initial and final set of the mortar is significantly delayed
Hydration rates between Portland cement and water are substantially reduced
Strength gain rates are reduced
Making matters even more challenging, cold masonry units can lower the temperature of
the mortar being used to place the units, contributing negatively to the already slow
reaction rate between cement and water, reduced strength gain rates, and delayed tooling
and setting times. In fact, if the masonry units are too cold and/or wet, freezing can cause
disruptive expansion and poor bonding. In addition to compromising the mortar
materials, the cold weather can also has an adverse effect on the performance of masons
who are now more concerned with comfort and safety than quality and efficiency.
A properly planned, designed and executed cold weather plan can maximize the
performance of masonry materials and masons to deliver expected desired results on time
and within budget. Certainly the severity of the weather, the type of project and location
of the job must be considered, but ultimately, sticking to a plan that is grounded in proven
best practices and techniques will help you deal with any cold weather situation.
Selecting Materials
Traditionally, masonry materials are selected to meet specific aesthetic and structural
characteristics for a project, but in cold weather, understanding how units and mortar will
best interact based on temperatures and other elements is just as important, if not more
so. There are several considerations we recommend when selecting masonry materials for
cold weather.
Use water content of the mortar that is below 6 percent to avoid disruptive
expansion caused by freezing (standard conditions call for water content in the 11
to 16 percent range)
Use accelerators to increase reaction rate of early-age strength development, but
do not substitute accelerators for other cold weather construction practices
(admixtures are not to be used unless specified)
Protecting, Storing and Heating Materials
All masonry materials should be protected from rain, snow, ice and other elements that
might jeopardize performance. We recommend the following tips for protecting, storing
and heating materials on cold weather projects.
Tightly wrap masonry units and mortar materials with canvas or polyethylene
tarps, and store off the ground to avoid moisture
Cover sand piles to prevent contamination with mud, clay and other harmful
Heat masonry materials to achieve a grout temperature of 40o F to 120o F at the
time of grout placement
Protecting Work Areas and Construction
The Specification for Masonry Structures provides requirements for certain cold weather
construction, but following the guidelines below will help make sure project site is set up
for safe and efficient work.
Install wind breaks when wind velocity exceeds 15 mph and daily mean
temperatures are between 20o F to 25o F
Provide heated enclosures that maintain a minimum temperature of 32o F in areas
with active masonry construction
Cover completed masonry work with a weather resistant cover for 24 hours when
mean daily temperatures on a job site are between 25o F to 40o F
Cover masonry work with insulating blankets for 24 hours when mean daily
temperatures on a job site are between 20o F to 25o F
For more information on cold weather masonry construction, contact your local
QUIKRETE bulk mortar sales representative or complete the Contact Us request form.